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[ASP.net教程]MVC生成图片验证码,可指定位数


前台:

<h2>mvc后台生成验证码,可指定位数</h2><img id="gc" src="GetValidateCode" onclick="this.src='GetValidateCode?r=' + Math.random()" /><button onclick="javascript:document.getElementById('gc').src='GetValidateCode?r=' + Math.random()">刷新</button>

 

后台:

 public ActionResult yzm()     {      return View();    }    /// <summary>    /// 创建验证码的图片    /// </summary>    /// <param name="containsPage">要输出到的page对象</param>    /// <param name="validateNum">验证码</param>    public byte[] CreateValidateGraphic(string validateCode)    {      Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 22);      Graphics g = Graphics.FromImage(image);      try      {        //生成随机生成器        Random random = new Random();        //清空图片背景色        g.Clear(Color.White);        //画图片的干扰线        for (int i = 0; i < 25; i++)        {          int x1 = random.Next(image.Width);          int x2 = random.Next(image.Width);          int y1 = random.Next(image.Height);          int y2 = random.Next(image.Height);          g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);        }        Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));        LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),         Color.Blue, Color.DarkRed, 1.2f, true);        g.DrawString(validateCode, font, brush, 3, 2);        //画图片的前景干扰点        for (int i = 0; i < 100; i++)        {          int x = random.Next(image.Width);          int y = random.Next(image.Height);          image.SetPixel(x, y, Color.FromArgb(random.Next()));        }        //画图片的边框线        g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);        //保存图片数据        MemoryStream stream = new MemoryStream();        image.Save(stream, ImageFormat.Jpeg);        //输出图片流        return stream.ToArray();      }      finally      {        g.Dispose();        image.Dispose();      }    }    public ActionResult GetValidateCode()    {      int code = new Random().Next(1000, 10000);      Session["ValidateCode"] = code;      byte[] bytes = CreateValidateGraphic(code.ToString());      return File(bytes, @"image/jpeg");    }